Effect of Ultraviolet Light-Exposed Mushrooms on Vitamin D Status: Liquid Chromatography-Tandem Mass Spectrometry Reanalysis of Biobanked Sera from a Randomized Controlled Trial and a Systematic Review plus Meta-Analysis

Background: Randomized controlled trial (RCT) data on the response of serum total 25-hydroxyvitamin D [25(OH) D] in healthy participants consuming UV light-exposed edible mushrooms are limited and mixed. Objective: The objective was to undertake a systematic review and meta-analysis of responses of serum 25(OH) D [and serum 25-hydroxyergocalciferol, 25(OH)D-2, and serum 25-hydroxycholecalciferol, 25(OH)D-3, if available] to consumption of UV-exposed mushrooms by healthy participants. Biobanked sera from one RCT (originally analyzed by immunoassay) were reanalyzed by LC-MS/MS to generate serum 25(OH)D-2 and serum 25(OH)D-3 data. Methods: Ovid MEDLINE, EMBASE, and Cochrane CENTRAL were searched for RCTs of UV-exposed mushrooms and data on serum 25(OH) D. Studies were screened for eligibility, and relevant data were extracted. Serum 25(OH) D data were re-analyzed by ANOVA and paired t tests. Results: Our structured search yielded 6 RCTs meeting our inclusion criteria. Meta-analysis of all 6 RCTs showed serum 25(OH) D was not significantly increased (P = 0.12) by UV-exposed mushrooms, but there was high heterogeneity (I-2 = 87%). Including only the 3 European-based RCTs [mean baseline 25(OH) D, 38.6 nmol/L], serum 25(OH) D was increased significantly by UV-exposed mushrooms [weighted mean difference (WMD): 15.2 nmol/L; 95% CI: 1.5, 28.8 nmol/L, P = 0.03, I-2 = 88%], whereas there was no significant effect in the 3 US-based RCTs [P = 0.83; mean baseline 25(OH) D: 81.5 nmol/L]. Analysis of serum 25(OH)D-2 and serum 25(OH)D-3 (n = 5 RCTs) revealed a statistically significant increase (WMD: 20.6 nmol/L; 95% CI: 8.0, 33.3 nmol/L, P = 0.001, I-2 = 99%) and decrease (WMD: 213.3 nmol/L; 95% CI: -15.8, -10.7 nmol/L, P < 0.00001, I-2 = 0%) after supplementation with UV-exposed mushrooms. Conclusions: Consumption of UV-exposed mushrooms may increase serum 25(OH) D when baseline vitamin D status is low via an increase in 25(OH)D-2 (24.2 nmol/L) and despite a concomitant but relatively smaller reduction in 25(OH)D-3 (212.6 nmol/L). When baseline vitamin D status is high, the mean increase in 25(OH)D-2 (18.3 nmol/L) and a relatively similar reduction in 25(OH)D-3 (213.6 nmol/L) may explain the lack of effect on serum 25(OH) D.